Study Reveals 30% of All Species Swap for Other Species Every 10 Years
By John C. Cannon
Life is reshuffling itself at an unsettling clip across Earth's surface and in its oceans, a new study has found.
The research, published Oct. 18 in the journal Science, drills into data from 239 studies that looked at changes in biodiversity over time. It reveals that almost 30 percent of all species are being swapped out for other species every 10 years.
Fish swim near a coral reef.
The sweeping hemorrhage of species across the planet continues to rattle scientists and conservationists. A recent report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services revealed that a million species or more could go extinct.
But squaring that global trend with what's happening at local levels has been difficult. At this level, research shows that the sheer number of species in many spots are holding steady or even going up. That's led some scientists to believe that species richness, an oft-used measure of biodiversity that tabulates the number of species living in a given area, provides an incomplete understanding of how life on Earth is changing.
"It is increasingly recognized that species richness alone cannot fully describe how biodiversity is changing," Shane Blowes, the paper's co-lead author and a postdoctoral researcher at the German Centre for Integrative Biodiversity Research in Halle-Jena-Leipzig, said in an email. "Species richness will continue to play an important role in our understanding of taxonomic diversity, but a more complete, nuanced picture of biodiversity change emerges when it is combined with other metrics."
The researchers found that 28 percent of species are being replaced each decade.
Blowes teamed up with ecologist Maria Dornelas and more than 20 other scientists from around the world to map changes in species richness as well as the composition of those local species groups across Earth's surface and oceans with an open-source database called BioTIME. Developed by Dornelas and her colleagues at the UK's University of St. Andrews, the BioTIME database gave the team access to more than 50,000 sets of data collected over time, known as time series, in nearly all of the world's ecosystems.
In 2014, Dornelas led a study revealing that the relative constancy of species numbers at local levels masked furtive changes in the identities of those species, which they referred to as reorganization. In the current research, the team found that this reorganization happens as species from elsewhere move in and replace the original inhabitants. As a result, the absolute number of species — captured as species richness — remains relatively constant, or might even go up.
"Their study thus highlights that the global biodiversity crisis, at least for now, is not primarily about decline but, rather, about large-scale reorganization," Britas Klemens Eriksson and Helmut Hillebrand wrote in a related commentary also in Science. Eriksson is an associate professor of marine ecology at the Netherlands' University of Groningen, and Hillebrand is a biologist at the Helmholtz Centre for Polar and Marine Research in Bremerhaven, Germany.
The researchers found that 28 percent of species are being replaced each decade.
Blowes, Dornelas and their colleagues also showed that reorganization isn't uniform. Indeed, it's happening much faster in certain "hotspots" around the globe, like tropical marine ecosystems. In the most volatile spots, turnover in species is happening twice as fast as it is on land. Blowes said that marine species are more sensitive to swings in temperature and they live in a relatively continuous ocean environment with few hurdles to their movement, which could explain the quicker turnover. But, he added, they needed more data to know why for sure.
On one hand, the variability of reorganization provides a measure of hope, at least in parts of the world.
"Our study shows biodiversity is changing everywhere, but we are not losing biodiversity everywhere," Dornelas said in a statement. "Some places are recovering and adapting."
However, the maps also show where the most worrying trends in species replacement are occurring.
"High rates of species losses are particularly concerning for tropical latitudes, because in the context of climate change there are likely fewer species capable of replacing species lost," Blowes said, "as tropical zones entering even warmer-temperature regimes have no current day equivalents."
Clarifying the differences in current biodiversity change across Earth's ecosystems could prove invaluable in conservation planning, the authors write.
"Mapping biodiversity change allowed us to identify regions of the world where rates of either species richness or compositional change are highest," Blowes said. "And our results should help refine hypotheses of where different drivers of biodiversity change might be most important."
Reposted with permission from our media associate Mongabay.
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EcoWatch Daily Newsletter
By Danielle Nierenberg
Following the murder of George Floyd by police in Minneapolis, people around the United States are protesting racism, police brutality, inequality, and violence in their own communities. No matter your political affiliation, the violence by multiple police departments in this country is unacceptable.
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By Jacob L. Steenwyk and Antonis Rokas
From the mythical minotaur to the mule, creatures created from merging two or more distinct organisms – hybrids – have played defining roles in human history and culture. However, not all hybrids are as fantastic as the minotaur or as dependable as the mule; in fact, some of them cause human diseases.
When Looking Through a Microscope Isn’t Close Enough.<p>For the last few years, <a href="http://www.rokaslab.org/" target="_blank">our team at Vanderbilt University</a>, <a href="https://www.researchgate.net/lab/Gustavo-Goldman-Lab" target="_blank">Gustavo Goldman's team at São Paulo University in Brazil</a> and many other collaborators around the world have been collecting samples of fungi from patients infected with different species of <em>Aspergillus</em> molds. One of the species we are particularly interested in is <a href="https://doi.org/10.1006/rwgn.2001.0082" target="_blank"><em>Aspergillus nidulans</em>, a relatively common and generally harmless fungus</a>. Clinical laboratories typically identify the species of <em>Aspergillus</em> causing the infection by examining cultures of the fungi under the microscope. The problem with this approach is that very closely related species of <em>Aspergillus</em> tend to look very similar in their broad morphology or physical appearance when viewing them through a microscope.</p><p>Interested in examining the varying abilities of different <em>A. nidulans</em> strains to cause disease, we decided to analyze their total genetic content, or genomes. What we saw came as a total surprise. We had not collected <em>A. nidulans</em> but <em>Aspergillus latus</em>, a close relative of <em>A. nidulans</em> and, as we were to soon find out, <a href="https://doi.org/10.1016/j.cub.2020.04.071" target="_blank">a hybrid species that evolved through the fusion of the genomes</a> of two other <em>Aspergillus</em> species: <em>Aspergillus spinulosporus</em> and an unknown close relative of <em>Aspergillus quadrilineatus</em>. Thus, we realized not only that these patients harbored infections from an entirely different species than we thought they were, but also that this species was the first ever <em>Aspergillus</em> hybrid known to cause human infections.</p>
Several Different Fungal Hybrids Cause Human Disease.<p>Hybrid fungi that can cause infections in humans are well known to occur in several different lineages of single-celled fungi known as yeasts. Notable examples include multiple different species of <a href="https://doi.org/10.1002/yea.3242" target="_blank">yeast hybrids</a> that cause the human diseases <a href="https://rarediseases.info.nih.gov/diseases/6218/cryptococcosis" target="_blank">cryptococcosis</a> and <a href="https://www.cdc.gov/fungal/diseases/candidiasis/index.html" target="_blank">candidiasis</a>. Although pathogenic yeast hybrids are well known, our discovery that the <em>A. latus</em> pathogen is a hybrid is a first for molds that cause disease in humans.</p>
(Left) Candida yeasts live on parts of the human body. Imbalance of microbes on the body can allow these yeasts, some of which are hybrids, to grow and cause infection. (Right) Cryptococcus yeasts, including ones that are hybrids, can cause life-threatening infections in primarily immunocompromised people. Centers for Disease Control and Prevention<p><a href="https://doi.org/10.1371/journal.ppat.1008315" target="_blank">Why certain <em>Aspergillus</em> species are so deadly</a> while others are harmless remains unknown. This may in part be because <a href="https://doi.org/10.1016/j.fbr.2007.02.007" target="_blank">combinations of traits, rather than individual traits</a>, underlie organisms' ability to cause disease. So why then are hybrids frequently associated with human disease? Hybrids inherit genetic material from both parents, which may result in new combinations of traits. This may make them more similar to one parent in some of their characteristics, reflect both parents in others or may differ from both in the rest. It is precisely this mix and match of traits that hybrids have inherited from their parental species that <a href="https://www.nytimes.com/2010/09/14/science/14creatures.html" target="_blank">facilitates their evolutionary success</a>, including their ability to cause disease.</p>
The Evolutionary Origin of an Aspergillus Hybrid.<p>Multiple evolutionary paths can lead to the emergence of hybrids. One path is through mating, just as the horse and donkey mate to create a mule. Another path is through the merging or fusion of genetic material from cells of different species.</p><p>It is this second path that appears to have been taken by our fungus. <em>A. latus</em> appears to have two of almost everything compared to its parental species: twice the genome size, twice the total number of genes and so on. But unlike other hybrids, which are often sterile like the mule, we found that <em>A. latus</em> is capable of reproducing both asexually and sexually.</p><p>But how distinct were the parents of <em>A. latus</em>? By comparing the parts contributed by each parent in the <em>A. latus</em> genome, we estimate that its parents are approximately 93% genetically similar, which is about as related as we humans are with lemurs. In other words, <em>A. latus</em>, an agent of infectious disease, is the fungal equivalent of a human-lemur hybrid.</p>
How A. Latus Differs From its Parents.<p>Elucidating the identity of closely related fungal pathogens and how they differ from each other in infection-relevant characteristics is a key step toward reducing the burden of fungal disease. For example, we found that <em>A. latus</em> was three times more resistant than <em>A. nidulans</em>, the species it was originally identified as using microscopy-based methods, to one of the most common antifungal drugs, <a href="https://www.drugbank.ca/drugs/DB00520" target="_blank">caspofungin</a>. This result provides a clear example of the potential importance of accurate identification of the <em>Aspergillus</em> pathogen causing an infection.</p><p>We also examined how <em>A. latus</em> and <em>A. nidulans</em> interact with cells from our immune system. We found that immune cells were less efficient at combating <em>A. latus</em> compared to <em>A. nidulans</em>, suggesting the hybrid fungus may be trickier for our immune systems to identify and destroy.</p><p>In the midst of the COVID-19 pandemic, our quest to understand <em>Aspergillus</em> pathogens is becoming more urgent. Growing evidence suggests that <a href="https://doi.org/10.1111/myc.13096" target="_blank">a fraction of COVID-19 patients are also infected with <em>Aspergillus</em>.</a> More worrying is that these <a href="https://doi.org/10.3201/eid2607.201603" target="_blank">secondary <em>Aspergillus</em> infections</a> can worsen the clinical outcomes for those infected with the novel coronavirus. That being said, we stress that little is known about <em>Aspergillus</em> infections in COVID-19 patients due to a lack of systematic testing, and none of the infections identified so far appear to have been caused by hybrids.</p><p>So, when it comes to hybrids, some are fantastic (the minotaur), some are helpful (the mule) and some are dangerous (<em>Aspergillus latus</em>). Understanding more about the biology of <em>Aspergillus latus</em> may help in our understanding of how microbial pathogens arise and how to best prevent and combat their infections.</p>
This Saturday, June 6, marks National Trails Day, an annual celebration of the remarkable recreational, scenic and hiking trails that crisscross parks nationwide. The event, which started in 1993, honors the National Trail System and calls for volunteers to help with trail maintenance in parks across the country.
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By John Letzing
This past Wednesday, when some previously hard-hit countries were able to register daily COVID-19 infections in the single digits, the Navajo Nation – a 71,000 square-kilometer (27,000-square-mile) expanse of the western US – reported 54 new cases of what's referred to locally as "Dikos Ntsaaígíí-19."
The Navajo Nation covers the corners of three different states. Google Maps
Growing Contribution<img lazy-loadable="true" src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzM3NDY5Ny9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTY0NjM4MTgyM30.IuQTKQs1stvYYKD6vaVTrqAyoBsUG0BhDvlhxsyKwPA/img.png?width=980" id="02a05" class="rm-shortcode" data-rm-shortcode-id="2841f82b1785df5d5ed7bf64d3bb882b" data-rm-shortcode-name="rebelmouse-image" />
World Economic Forum
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World Environment Day: A Time to Consider the Planet We’ll Return To, and Decide How to Care for It Going Forward
It's a different kind of World Environment Day this year. In prior years, it might have been enough to plant a tree, spend some extra time in the garden, or teach kids the importance of recycling. This year we have heavier tasks at hand. It's been months since we've been able to spend sufficient time outside, and as we lustfully watch the beauty of a new spring through our kitchen's glass windows, we have to decide how we'll interact with the natural world on our release, and how we can prevent, or be equipped to handle, future threats against our wellbeing.